1. Field of the Invention
The present invention relates to a semiconductor device formed by using a droplet discharge method, typified by an ink-jet method and a manufacturing method thereof.
2. Description of the Related Art
Conventionally, a so-called active matrix driving type display panel or a semiconductor integrated circuit including a semiconductor element typified by a thin film transistor (hereinafter also referred to as a “TFT”) over a glass substrate is manufactured by patterning various thin films through a light-exposure step (hereinafter referred to as a photolithography step) using a photo mask.
In a photolithography step, after a resist is applied to an entire surface of a substrate to perform prebaking, ultraviolet ray or the like is irradiated through a photo mask, and thus, development is performed to form a resist pattern. Thereafter, a thin film (a film formed from a semiconductor material, an insulating material or a conductive material) existing in a portion to be a film pattern using the resist pattern as a mask pattern is etched and removed to pattern the thin film; thus, the film pattern is formed.
In addition, a technique for forming a film over a semiconductor wafer by using a device which can discharge a resist continuously from a nozzle in a linear shape with a fine diameter to reduce loss of a raw material required for forming the film is mentioned in Reference 1 (Reference 1: Japanese Patent Application Laid-Open No. 2000-188251).
However, in a step of forming a film pattern using a conventional photolithography step, there is a problem that throughput is reduced due to a number of steps of forming a mask pattern, as well as wasting most parts of the material of a film pattern and a resist.
In addition, a photolithography device used for a photolithography step has difficulty in performing light-exposure treatment to a large-sized substrate at once. Therefore, in a method for manufacturing a semiconductor device using a large-sized substrate, there is a problem that a yield is reduced since a plurality of light exposing times are required and unconformity with an adjacent pattern is generated.
Moreover, a solution having small diameter of a droplet is required to be discharged to form a minute semiconductor element having a small occupied area by using a droplet discharge method with the technique disclosed in Reference 1. For this purpose, the diameter of a discharge opening may be made small. However, in this case, the composition of the discharging solution is attached, dried and solidified at the end of the discharge opening and clogging or the like is generated. Thus, it is difficult to continuously and stably discharge a certain amount of discharge solution. Consequently, there is a problem that throughput or a yield of a semiconductor device formed from the semiconductor element is deteriorated.